/*
  ==============================================================================

   This file is part of the JUCE framework.
   Copyright (c) Raw Material Software Limited

   JUCE is an open source framework subject to commercial or open source
   licensing.

   By downloading, installing, or using the JUCE framework, or combining the
   JUCE framework with any other source code, object code, content or any other
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   Agreement, and all incorporated terms including the JUCE Privacy Policy and
   the JUCE Website Terms of Service, as applicable, which will bind you. If you
   do not agree to the terms of these agreements, we will not license the JUCE
   framework to you, and you must discontinue the installation or download
   process and cease use of the JUCE framework.

   JUCE End User Licence Agreement: https://juce.com/legal/juce-8-licence/
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   Or:

   You may also use this code under the terms of the AGPLv3:
   https://www.gnu.org/licenses/agpl-3.0.en.html

   THE JUCE FRAMEWORK IS PROVIDED "AS IS" WITHOUT ANY WARRANTY, AND ALL
   WARRANTIES, WHETHER EXPRESSED OR IMPLIED, INCLUDING WARRANTY OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, ARE DISCLAIMED.

  ==============================================================================
*/

namespace juce
{

AffineTransform::AffineTransform (float m00, float m01, float m02,
                                  float m10, float m11, float m12) noexcept
 :  mat00 (m00), mat01 (m01), mat02 (m02),
    mat10 (m10), mat11 (m11), mat12 (m12)
{
}

bool AffineTransform::operator== (const AffineTransform& other) const noexcept
{
    const auto tie = [] (const AffineTransform& a)
    {
        return std::tie (a.mat00, a.mat01, a.mat02, a.mat10, a.mat11, a.mat12);
    };

    return tie (*this) == tie (other);
}

bool AffineTransform::operator!= (const AffineTransform& other) const noexcept
{
    return ! operator== (other);
}

//==============================================================================
bool AffineTransform::isIdentity() const noexcept
{
    return operator== (AffineTransform());
}

const AffineTransform AffineTransform::identity (1.0f, 0.0f, 0.0f, 0.0f, 1.0f, 0.0f);

//==============================================================================
AffineTransform AffineTransform::followedBy (const AffineTransform& other) const noexcept
{
    return { other.mat00 * mat00 + other.mat01 * mat10,
             other.mat00 * mat01 + other.mat01 * mat11,
             other.mat00 * mat02 + other.mat01 * mat12 + other.mat02,
             other.mat10 * mat00 + other.mat11 * mat10,
             other.mat10 * mat01 + other.mat11 * mat11,
             other.mat10 * mat02 + other.mat11 * mat12 + other.mat12 };
}

AffineTransform AffineTransform::translated (float dx, float dy) const noexcept
{
    return { mat00, mat01, mat02 + dx,
             mat10, mat11, mat12 + dy };
}

AffineTransform AffineTransform::translation (float dx, float dy) noexcept
{
    return { 1.0f, 0.0f, dx,
             0.0f, 1.0f, dy };
}

AffineTransform AffineTransform::withAbsoluteTranslation (float tx, float ty) const noexcept
{
    return { mat00, mat01, tx,
             mat10, mat11, ty };
}

AffineTransform AffineTransform::rotated (float rad) const noexcept
{
    auto cosRad = std::cos (rad);
    auto sinRad = std::sin (rad);

    return { cosRad * mat00 - sinRad * mat10,
             cosRad * mat01 - sinRad * mat11,
             cosRad * mat02 - sinRad * mat12,
             sinRad * mat00 + cosRad * mat10,
             sinRad * mat01 + cosRad * mat11,
             sinRad * mat02 + cosRad * mat12 };
}

AffineTransform AffineTransform::rotation (float rad) noexcept
{
    auto cosRad = std::cos (rad);
    auto sinRad = std::sin (rad);

    return { cosRad, -sinRad, 0,
             sinRad,  cosRad, 0 };
}

AffineTransform AffineTransform::rotation (float rad, float pivotX, float pivotY) noexcept
{
    auto cosRad = std::cos (rad);
    auto sinRad = std::sin (rad);

    return { cosRad, -sinRad, -cosRad * pivotX +  sinRad * pivotY + pivotX,
             sinRad,  cosRad, -sinRad * pivotX + -cosRad * pivotY + pivotY };
}

AffineTransform AffineTransform::rotated (float angle, float pivotX, float pivotY) const noexcept
{
    return followedBy (rotation (angle, pivotX, pivotY));
}

AffineTransform AffineTransform::scaled (float factorX, float factorY) const noexcept
{
    return { factorX * mat00, factorX * mat01, factorX * mat02,
             factorY * mat10, factorY * mat11, factorY * mat12 };
}

AffineTransform AffineTransform::scaled (float factor) const noexcept
{
    return { factor * mat00, factor * mat01, factor * mat02,
             factor * mat10, factor * mat11, factor * mat12 };
}

AffineTransform AffineTransform::scale (float factorX, float factorY) noexcept
{
    return { factorX, 0, 0, 0, factorY, 0 };
}

AffineTransform AffineTransform::scale (float factor) noexcept
{
    return { factor, 0, 0, 0, factor, 0 };
}

AffineTransform AffineTransform::scaled (float factorX, float factorY,
                                         float pivotX, float pivotY) const noexcept
{
    return { factorX * mat00, factorX * mat01, factorX * mat02 + pivotX * (1.0f - factorX),
             factorY * mat10, factorY * mat11, factorY * mat12 + pivotY * (1.0f - factorY) };
}

AffineTransform AffineTransform::scale (float factorX, float factorY,
                                        float pivotX, float pivotY) noexcept
{
    return { factorX, 0, pivotX * (1.0f - factorX),
             0, factorY, pivotY * (1.0f - factorY) };
}

AffineTransform AffineTransform::shear (float shearX, float shearY) noexcept
{
    return { 1.0f,   shearX, 0,
             shearY, 1.0f,   0 };
}

AffineTransform AffineTransform::sheared (float shearX, float shearY) const noexcept
{
    return { mat00 + shearX * mat10,
             mat01 + shearX * mat11,
             mat02 + shearX * mat12,
             mat10 + shearY * mat00,
             mat11 + shearY * mat01,
             mat12 + shearY * mat02 };
}

AffineTransform AffineTransform::verticalFlip (float height) noexcept
{
    return { 1.0f,  0.0f, 0.0f,
             0.0f, -1.0f, height };
}

AffineTransform AffineTransform::inverted() const noexcept
{
    double determinant = getDeterminant();

    if (! approximatelyEqual (determinant, 0.0))
    {
        determinant = 1.0 / determinant;

        auto dst00 = (float) ( mat11 * determinant);
        auto dst10 = (float) (-mat10 * determinant);
        auto dst01 = (float) (-mat01 * determinant);
        auto dst11 = (float) ( mat00 * determinant);

        return { dst00, dst01, -mat02 * dst00 - mat12 * dst01,
                 dst10, dst11, -mat02 * dst10 - mat12 * dst11 };
    }

    // singularity..
    return *this;
}

bool AffineTransform::isSingularity() const noexcept
{
    return exactlyEqual (mat00 * mat11 - mat10 * mat01, 0.0f);
}

AffineTransform AffineTransform::fromTargetPoints (float x00, float y00,
                                                   float x10, float y10,
                                                   float x01, float y01) noexcept
{
    return { x10 - x00, x01 - x00, x00,
             y10 - y00, y01 - y00, y00 };
}

AffineTransform AffineTransform::fromTargetPoints (float sx1, float sy1, float tx1, float ty1,
                                                   float sx2, float sy2, float tx2, float ty2,
                                                   float sx3, float sy3, float tx3, float ty3) noexcept
{
    return fromTargetPoints (sx1, sy1, sx2, sy2, sx3, sy3)
            .inverted()
            .followedBy (fromTargetPoints (tx1, ty1, tx2, ty2, tx3, ty3));
}

bool AffineTransform::isOnlyTranslation() const noexcept
{
    return exactlyEqual (mat01, 0.0f)
        && exactlyEqual (mat10, 0.0f)
        && exactlyEqual (mat00, 1.0f)
        && exactlyEqual (mat11, 1.0f);
}

bool AffineTransform::isOnlyTranslationOrScale() const noexcept
{
    return exactlyEqual (mat01, 0.0f) && exactlyEqual (mat10, 0.0f);
}

float AffineTransform::getDeterminant() const noexcept
{
    return (mat00 * mat11) - (mat01 * mat10);
}

float AffineTransform::getScaleFactor() const noexcept
{
    return (std::abs (mat00) + std::abs (mat11)) / 2.0f;
}


//==============================================================================
//==============================================================================
#if JUCE_UNIT_TESTS

class AffineTransformTests final : public UnitTest
{
public:
    AffineTransformTests()
        : UnitTest ("AffineTransform", UnitTestCategories::maths)
    {}

    void runTest() override
    {
        beginTest ("Determinant");
        {
            constexpr float scale1 = 1.5f, scale2 = 1.3f;

            auto transform = AffineTransform::scale (scale1)
                                             .followedBy (AffineTransform::rotation (degreesToRadians (72.0f)))
                                             .followedBy (AffineTransform::translation (100.0f, 20.0f))
                                             .followedBy (AffineTransform::scale (scale2));

            expect (approximatelyEqual (std::sqrt (std::abs (transform.getDeterminant())), scale1 * scale2));
        }

        beginTest ("fromTargetPoints");
        {
            const Point a (0.0f, 0.0f);
            const Point b (1.0f, 0.0f);
            const Point c (0.0f, 1.0f);
            const Point translation (1.0f, 1.0f);
            const auto transform = AffineTransform::fromTargetPoints (a, a + translation,
                                                                      b, b + translation,
                                                                      c, c + translation);
            expect (exactlyEqual (transform.mat00, 1.0f));
            expect (exactlyEqual (transform.mat01, 0.0f));
            expect (exactlyEqual (transform.mat02, translation.x));

            expect (exactlyEqual (transform.mat10, 0.0f));
            expect (exactlyEqual (transform.mat11, 1.0f));
            expect (exactlyEqual (transform.mat12, translation.y));
        }
    }
};

static AffineTransformTests timeTests;

#endif

} // namespace juce
